Selecting between normal and virtual dual layer ack/nack

ABSTRACT

An allocation of downlink resources is received, which are monitored on l layers for data. A resource-specific bit (ACK/NACK) is generated for each of those resources. From a pattern of those resources is selected an algorithm from among a first algorithm that bundles them in a first mode and a second algorithm that bundles them in a second mode. The selected algorithm is used on the generated resource-specific bits that correspond to the downlink resources, bundled according to the selected mode, to generate l reply bits which are then transmitted. At the network side a NACK reply bit is received, based on a pattern of the allocated downlink resources, a first algorithm that bundles them in a first mode or a second algorithm that bundles them in a second mode is selected. A bundling window and layer combination are determined from the selected algorithm, which gives the resource for retransmitting the NACK&#39;d data.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/465,954, filed Aug. 22, 2014, entitled “SELECTING BETWEEN NORMAL ANDVIRTUAL DUAL LAYER ACK/NACK,” which is a continuation of U.S.application Ser. No. 13/770,384, filed Feb. 19, 2013, now U.S. Pat. No.8,861,472, entitled “SELECTING BETWEEN NORMAL AND VIRTUAL DUAL LAYERACK/NACK,” which is a continuation of U.S. application Ser. No.12/459,352, filed Jun. 30, 2009, now U.S. Pat. No. 8,396,030, entitled“SELECTING BETWEEN NORMAL AND VIRTUAL DUAL LAYER ACK/NACK,” which claimspriority to U.S. Application, 61/133,476, filed Jun. 30, 2008, entitled“SELECTING BETWEEN NORMAL AND VIRTUAL DUAL LAYER ACK/NACK” the contentsof which are hereby incorporated by reference in their entirety.

BACKGROUND

1. Technical Field

The teachings herein relate generally to control signaling in wirelessnetworks, and particular embodiments detail ACK/NACK signaling for datareceived in grouped downlink resources.

2. Related Art

The following abbreviations and terms are herewith defined:

-   -   3GPP third generation partnership project    -   ACK acknowledgement    -   DL downlink    -   DTX discontinuous transmission    -   eNB Base Station/Node B of an LTE system    -   E-UTRAN evolved UTRAN    -   FDD: frequency division duplex    -   H-ARQ hybrid automatic repeat (or retransmission) request    -   LTE long term evolution of 3GPP (also known as 3.9G)    -   MCS modulation and coding set (or scheme)    -   MIMO multiple input multiple output (related to antenna        configuration)    -   NACK negative ACK    -   Node B base station or similar network access node    -   OFDM orthogonal frequency division multiplex    -   PDCCH physical downlink control channel    -   PDSCH physical downlink shared channel    -   PMI precoding matrix index    -   PRB physical resource block    -   PUCCH physical uplink control channel    -   PUSCH physical uplink shared channel    -   TDD time division duplex    -   UE user equipment (e.g., mobile equipment/station)    -   UL uplink    -   UMTS universal mobile telecommunications system    -   UTRAN UMTS terrestrial radio access network

3GPP is standardizing the long-term evolution (LTE) of the radio-accesstechnology which aims to achieve reduced latency, higher user datarates, improved system capacity and coverage, and reduced cost for theoperator. The current understanding of LTE relevant to these teachingsmay be seen at 3GPP TR 36.213 v8.3.0 (2008 May) entitled PHYSICAL LAYERPROCEDURES (RELEASE 8), which is attached to the priority document asExhibit A. Both FDD and TDD are considered in LTE, and the non-limitingexamples of the invention detailed below are described within thecontext of the TDD mode.

Allocations of radio resources are given in LTE on the PDCCH. Aparticular UE listens to the PDCCH at its designated time and sees if itis allocated UL and/or DL resources. If this is the case, the UE mapsthe allocation information in the PDCCH to the PDSCH or PUSCH as thecase may be. In the case of an UL allocation, the UE sends its data onthe allocated UL resource and maps that resource to a control channelwhere it listens for the eNB's ACK/NACK for the UL data. In the case ofa DL allocation, the UE tunes to the mapped DL resource and monitors fordata from the eNB, and maps that DL resource to a control channel whereit then sends its ACK/NACK for the DL data (specifically, the lowestcontrol channel element index of the PDCCH which carries the DL controlinformation DCI maps to the UL channel which carries the ACK/NACK). EachPDCCH gives multiple allocations, and the typical scenario is that therewill be more DL allocations than UL in a given PDCCH. These teachingsassume that typical scenario.

LTE reduces control signalling in certain instances as compared to priorwireless protocols in order to conserve radio resources for the transferof user data, and also to more efficiently use the UE's limited powersupply. As noted above, LTE allows a frame configuration in which thereare more DL subframes than UL subframes, which causes difficulty forone-to-one mapping of the allocated resource to its ACK/NACK. One way toaddress these issues is to send a single ACK/NACK for data received overa group of DL resources. Reference in this regard may be had to documentR1-081110 (3GPP TSG-RAN WG1 #52, Sorrento, Italy, Feb. 11-15, 2008, byEricsson, Motorola, Nokia, Nokia Siemens Networks and Qualcomm) entitledMultiple ACK/NACK for TDD and attached to the priority document asExhibit B. That document states that for LTE it is agreed that ULhybrid-ARQ acknowledgements in TDD can be transmitted as a singleACK/NACK feedback where ACK/NACKs from one or several DL subframes arecombined. This is termed ‘bundling’ the ACKs/NACKs, and is performed bya logical AND operation on the ACKs/NACKs for the various DL resourcesto generate a single ACK/NACK report, which allows the PUCCH formatsalready defined for LTE to be reused (PUCCH Format 1/1A/1B). ThisACK/NACK mode has broadly been named “AN-bundling” (where AN is shortfor ACK/NACK). It is to be hard-coded (from specifications; e.g., TS36.213 at Exhibit A of the priority document) as to which DL subframesare jointly acknowledged in which UL subframe, and thus depends on whichTDD configuration is active.

When a UE is configured for dual layer reception (e.g. MIMO), it carriestwo bits on its uplink ACK/NACK channel. These bits are needed toacknowledge each of the layers (the term layers and streams are usedinterchangeably). However, if the UE is not assigned exactly the samePRB resources (or transmission parameters) in all subframes within theACK/NACK bundling window it will have limited correlation betweensubframes for a certain layer (or stream), in which case a bundledACK/NACK of such stream becomes meaningless.

The inventors have recognized this previously and determined that forthe above case it would be better to use to those two bits for creatingsmaller sub-bundling windows to achieve a gain. Such sub-bundling hasbeen described for single stream case by the inventors in U.S.Provisional Patent Application Ser. No. 61/029,361 entitled “VirtualDual-Stream Transmission to Reduce PDCCH Reliability Problem forDownlink-Heavy LTE TDD”, attached to the priority document as Exhibit C.

The above-referenced provisional patent application considers how toconfigure a UE to do virtual dual-stream transmission and describes thatit could be integrated with MIMO. Higher layer configuration may be usedin order to optimize the use of the bits.

SUMMARY

In a first aspect thereof the exemplary embodiments of this inventionprovide a method comprising: receiving an allocation of downlinkresources and monitoring the allocated downlink resources on l layersfor data (l is a positive integer); generating a resource-specific bitfor each of the respectively monitored allocated downlink resources;based on a pattern of the allocated downlink resources, selecting fromamong at least a first algorithm that bundles the downlink resources ina first mode and a second algorithm that bundles the downlink resourcesin a second mode; using the selected first or second algorithm on thegenerated resource-specific bits that correspond to the downlinkresources as bundled according to the respective first or second mode togenerate l reply bits; and transmitting the generated l reply bits.

In a second aspect thereof the exemplary embodiments of this inventionprovide an apparatus comprising at least one receiver, at least oneprocessor and at least one transmitter. The at least one receiver isconfigured to receive an allocation of downlink resources and to monitorthe allocated downlink resources on l layers for data (l is an integer).The at least one processor is configured to generate a resource-specificbit for each of the respectively monitored allocated downlink resources;and to select from among at least a first algorithm that bundles thedownlink resources in a first mode and a second algorithm that bundlesthe downlink resources in a second mode, in which the selection is basedon a pattern of the allocated downlink resources; and the processor isfurther configured to use the selected first or second algorithm on thegenerated resource-specific bits that correspond to the downlinkresources as bundled according to the respective first or second mode togenerate l reply bits. The at least one transmitter is configured totransmit the generated l reply bits.

In a third aspect thereof the exemplary embodiments of this inventionprovide a method comprising: sending an allocation of downlink resourcesand transmitting data on the allocated downlink resources; responsive toreceiving a reply bit that is a negative acknowledgement of thetransmitted data, selecting from among at least a first algorithm thatbundles the downlink resources in a first mode and a second algorithmthat bundles the downlink resources in a second mode based on a patternof the allocated downlink resources; determining a bundling window andlayer combination from the selected algorithm; and retransmitting thedata that is the subject of the negative acknowledgement in theallocated downlink resources which are indicated by the bundling windowand layer combination.

In a fourth aspect thereof the exemplary embodiments of this inventionprovide an apparatus comprising receiving means, processing means andsending means. The receiving means is for receiving an allocation ofdownlink resources and for monitoring the allocated downlink resourceson l layers for data, (l is an integer). The processing means is forgenerating a resource-specific bit for each of the respectivelymonitored allocated downlink resources, and for selecting from among atleast a first algorithm that bundles the downlink resources in a firstmode and a second algorithm that bundles the downlink resources in asecond mode based on a pattern of the allocated downlink resources, andfor using the selected first or second algorithm on the generatedresource-specific bits that correspond to the downlink resources asbundled according to the respective first or second mode to generate lreply bits. The sending means is for transmitting the generated l replybits.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects of these teachings are made more evidentin the following Detailed Description, when read in conjunction with theattached Drawing Figures.

FIG. 1 is an illustration of a sub-bundling principle for TDDconfiguration #5 for a single-layer UE.

FIG. 2 illustrates at the uppermost timing diagram an illustration of a‘normal’ dual-layer transmission and at the lowermost timing diagram a‘virtual’ dual-layer transmission according to an exemplary embodimentof the invention.

FIG. 3 is a simplified block diagram of various electronic devices thatare suitable for use in practicing the exemplary embodiments of thisinvention.

FIG. 4 is a process flow diagram according to an exemplary embodiment ofthe invention.

DETAILED DESCRIPTION

This section is intended to provide a background or context to theinvention that is recited in the claims. The description herein mayinclude concepts that could be pursued, but are not necessarily onesthat have been previously conceived or pursued. Therefore, unlessotherwise indicated herein, what is described in this section is notprior art to the description and claims in this application and is notadmitted to be prior art by inclusion in this section.

It is initially noted that the examples and explanations below are inthe context of a LTE network, but embodiments of this invention are notso limited and may be employed in any network protocol, such as forexample UTRAN (universal mobile telecommunications system terrestrialradio access network), GSM (global system for mobile communications),WCDMA (wideband code division multiple access, also known as 3G orUTRAN), WLAN (wireless local area network), WiMAX (worldwideinteroperability for microwave access) and the like, in which downlinktransmissions are multiplexed to different users. Further, the variousnames used in the description below (e.g., PDCCH, PRB, etc.) are notintended to be limiting in any respect but rather serve asparticularized examples directed to specific LTE implementations usingcurrent LTE terms for a clearer understanding of the invention. Theseterms/names may be later changed in LTE and they may be referred to byother terms/names in different network protocols, and these teachingsare readily adapted and extended to such other protocols.

As an initial matter, first is detailed the inventors' proposal for LTEfor a single layered UE which is used later below to explain basics ofthe virtual dual-layer ACK/NACK signaling for a dual-layer configured UEaccording to these teachings.

Single-Layer ACK/NACK Bundling:

ACK/NACK bundling solutions have been decided in order for UE toacknowledge multiple DL assignments with a single ACK in uplink. A 2-bitDownlink Assignment Index (DAI) field has been proposed which provides agood solution for all TDD configurations except for TDD configuration #5shown in Table 1 below (D=DL, U=UL, S=DL subframe switching from DL toUL).

TABLE 1 Uplink and Downlink Allocations Config- Switch-point Subframenumber uration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S U UU 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms  D S U UU D D D D D 4 10 ms  D S U U D D D D D D 5 10 ms  D S U D D D D D D D 65 ms D S U U U D S U U D

Some modifications to the Downlink Assignment Index can be made tosupport up to full activity in downlink (e.g. 9 DL assignments for eachACK/NACK bundling window) while still supporting a single ACK bit inuplink. This still causes a large number of retransmissions and thus areduction of spectral efficiency. It has therefore been proposed inmultiple contributions that higher order ACK/NACK be used to improve theperformance.

The context is the special case of having 2 ACK bits available; e.g.equivalent to dual layer MIMO ACK/NACK which requires the same PUCCHresource reservation as single layer ACK/NACK although a better linkbudget. This is the most simple case and with some simple rules for TDDconfiguration 9DL:1UL, it will be shown that performance can be improvedwith minimal changes to current LTE procedures.

For TDD configuration #5 of Table 1 there are 9 DL subframes associatedwith 1 UL subframe. For a single layer configured UE and the 9 subframeACK/NACK bundling window, first divide it into two sub-bundling windowsas illustrated in FIG. 1. A hard-coded split such as that shown in FIG.1 is then imposed in order to bundle subframes where it is likely thatscheduling decisions within the sub-bundling window have been made basedon a same CQI report.

Again use the assumption of a single ACK/NACK channel but now use theflexibility of QPSK (quaternary phase shift keying) transmission toallow for larger downlink scheduling flexibility. Denote the ACK/NAKbits as (b₁, b₂) for each of the two sub-bundling windows shown in FIG.1 (subframes 1-5 and subframes 6-9). As just one particular example, thetransmitted symbols as a function of the ACK/NACK state of each of thesub-bundling windows are shown in Table 2 (an exact constellationmapping can be different without departing from these teachings).

TABLE 2 Example transmission depending on sub-bundling window state 1stsub-bundling 2nd sub-bundling Transmission on window window ACK/NACKchannel ACK DTX +1 NACK DTX −1 DTX DTX  0 ACK ACK  (1 − j) · 1/√2 NACKACK (−1 − j) · 1/√2 DTX ACK −j ACK NACK  (1 + j) · 1/√2 NACK NACK (−1 +j) · 1/√2 DTX NACK  j

One design principle is to transmit multiple ACK/NACK bits on a singleACK/NACK channel using PUCCH formats 1a/1b. With this approach, noadditional PUCCH resource needs to be reserved for the transmission ofmultiple ACK/NACK bits.

This approach to single-layer transmission easily re-uses the DownlinkAssignment Index definitions for the 4-subframe sub-bundling window andcan also be used for the 5-subframe sub-bundling window if limiting theUE to 4/5 dynamic DL assignments in that window. Alternatively, methodsproposed for single ACK/NACK for TDD configuration #5 can be used hereas well to allow a UE to access 100% of the DL capacity.

Via its UL link adaptation methods, the eNB can for each duplexingperiod of 10 ms predict if a UE can support 2-bit ACK/NACK so that itcan schedule more than 4 DL assignments to a UE. If only “1-bit”ACK/NACK can be supported, the scheduling flexibility is limited toschedule the user in only a single sub-bundling window. By making smartmapping of sub-bundling windows to match CQI latencies, this is expectedto be a minor limitation in practice.

Dual-Layer ACK/NACK Bundling:

Now consider the case where the UE is capable of dual layertransmissions, and the DL resources the UE monitors for its data must beACK/NACK'd on each stream/layer. Embodiments of this invention fordual-layer bundling specify a behavior rule, known in advance to boththe eNB and the UE, that determines/dictates how the 2 ACK/NACK bitsshould be used depending on the received scheduling pattern and thenature of the scheduling pattern for the DL resources over which thedata is to be received. Essentially, each DL resource will generate anACK or NACK. At this point the generated ACK/NACK is not sent, so termeach of these bits intermediate bits or resource-specific bits. The UEselects one or another of two different algorithms to logically combine(AND) various ones of those resource-specific ACK/NACKs, and theselection is based on the scheduling pattern of the resource allocationitself. The UE then logically combines the individual ACK/NACK'saccording to the selected algorithm and only then sends the ACK/NACKthat is a single bit representing the logical combination of the bundledresources. Because there are two layers the UE generates two bits, but asingle selection based on the DL pattern is used to generate them both.

To illustrate an exemplary embodiment of the invention, consider FIG. 2.Like FIG. 1, this is an illustration of TDD configuration #5 (9DL:1UL)but for a dual layer UE. Note that this example is non-limiting andthese teachings may be used generally for all TDD configurations whereACK/NACK bundling is specified (e.g. when DL resources exceed the amountof UL resources). As well these teachings may also be extended to otherwireless protocols.

It is useful to first discuss the two ways a UE can use its ACK/NACKbits. As it has been configured (higher layer) to be a dual-layer UE, italways has 2 bits available (QPSK symbol). At the topmost timing diagramof FIG. 2 is shown what we consider for simplicity a default or ‘normal’mode. There are nine DL subframes in each of the first and second layer.The UE creates two ACK/NACK bits, one for each of the layers and eachaggregating using the AND operation the individual ACK/NACKs the UEdetermined for each DL subframe. Define as a_(n,l) the ACK/NACKcorresponding to subframe n (where n ranges from 1 to 9 DL subframes forthe example of FIG. 2) and layer l (where l ranges from 1 to 2 for thedual layer example of FIG. 2). Then the UE creates its two ACK/NACK bitsas:

-   -   A₁=AND(a_(1.1), a_(2.1), a_(3.1), a_(4.1), a_(5.1), a_(6.1),        a_(7.1), a_(8.1), a_(9.1))    -   A₂=AND(a_(1.2), a_(2.2), a_(3.2), a_(4.2), a_(5.2), a_(6.2),        a_(7.2), a_(8.2), a_(9.2))

In this instance the aggregated bit A₁ aggregates all theresource-specific ACK/NACK bits in layer 1, and the aggregated bit A₂aggregates all the resource-specific ACK/NACK bits of layer 2. Note thatthis is a simple logical AND function across all the DL subframes for anindividual layer. This is an extension of the single-layer ACK/NACKprocedure noted above and so we term this the ‘normal’ dual-layerconfiguration in terms of ACK/NACK.

The second mode can also be called sub-bundling but instead we term thisas using a ‘virtual’ dual-layer transmission in terms of ACK/NACK. Anexample is shown at the lowermost timing diagram of FIG. 2. Like FIG. 1,the sub-bundling splits between subframes 1-5 and subframes 6-9. Thereare still two layers and so two ACK/NACK bits are transmitted. But inthis ‘virtual’ dual-layer transmission the first bit is aggregated fromall the ACK/NACK's of the individual DL resources in both/all layers fora first subset of the allocated DL resources, and the second bit isaggregated from all the ACK/NACK's of the individual DL resources inboth/all layers for a second subset of the allocated DL resources (wherethe first and second subsets do not overlap and fully encompass thewhole of the allocated DL resources, consistent with the sub-bundlingconcept in general). It can be seen that the DL subframes within thebundling window are divided into two parts and for each part is createda separate ACK/NACK. Using the specific example of 5/4 split shown inthe lowermost timing diagram of FIG. 2, the two ACK/NACK bits arecreated as:

-   -   A₁=AND(a_(1.1), a_(2.1), a_(3.1), a_(4.1), a_(5.1), a_(1.2),        a_(2.2), a_(3.2), a_(4.2), a_(5.2))    -   A₂=AND(a_(6.1), a_(7.1), a_(8.1), a_(9.1), a_(6.2), a_(7.2),        a_(8.2), a_(9.2))

In this instance the aggregated bit A₁ aggregates all theresource-specific ACK/NACK bits of all layers (both layers in thisexample) for only a first sub-set of the subframes (subframes 1-5 inthis example), and the aggregated bit A₂ aggregates all theresource-specific ACK/NACK bits of all layers for only a second subsetof the subframes (subframes 6-9 in this example). Like the ‘normal’transmission detailed above this is a simple logical AND function, butunlike that ‘normal’ algorithm this ACK is across all the layers for asubset of the DL subframes for an individual layer. Said another way, weACK across the layers and then divide ACK/NACK into the time domain,whereas the ‘normal’ approach ACKs across all DL subframes and dividesthe two ACK bits by the spatial domain.

One aspect of this invention is to be able to switch between thereporting modes, i.e. handling how the AND operation is performed.Whether there is 5/4 division or a 4/5 division or any other division ofthe sub-bundles/window sizes makes no difference to the underlyingconcept of different aggregations to generate the ACK/NACK for differentpatterns of DL resources.

For a correct interpretation between the eNB and the UE it is importantthat the same mode is assumed at both ends of the transmission/receptionlink. To this end there is a need for a set of standardized rules, sothe mode does not need to be signaled explicitly. This can be done byhigher layer configuration (e.g., medium access control layer, or someother layer higher than the physical layer). Until that can be adoptedfor LTE (e.g., Release 9), there is proposed a dynamic rule thatautomatically selects the best method in a way which is clear withoutambiguity to both the eNB and the UE.

To understand one particular motivation behind the invention, it isuseful to detail in which situation the two modes are preferred. When weAND the individual ACK/NACKs it is best for the communication system ifthose individual ACK/NACKs are as correlated as possible. Otherwisethere is an unnecessary amount of retransmission ongoing. With that inmind two rules or guidelines are presented:

-   -   1. Use the normal dual-layer ACK/NACK method when the DL        assignments to the UE are highly correlated in time so that the        decorrelation is larger between the two MIMO layers. This is        e.g. when UE has been assigned to the very same resources        throughout the ACK/NACK bundling window. [the term “very same        resources” is detailed below]    -   2. Use the virtual dual-layer ACK/NACK method when successive DL        assignments are not correlated in time and frequency so that        ANDing MIMO layers have no real meaning. In this case it is        preferred to have the gain of time-distributed ACK/NACK.

The inventors' simulations show that for single-layer transmission thegain from going from the normal to the virtual ACK/NACK method is 11%,so a significant gain is expected for this feature. To this end isdetailed a change criterion that is defined so that UE can determine ifthere is large correlation in time or not. This change criterion is usedto identify the “very same resources” noted above. The algorithm thatwould be used in the UE to determine the ACK/NACK method to use (andalso in eNB based on its own created DL assignments so that it caninterpret ACK/NACK correctly) is in an exemplary embodiment formulatedas follows:

IF change criterion exceeded    USE virtual dual-layer ACK/NACK method.OTHERWISE    USE normal dual-layer ACK/NACK method ENDThis algorithm runs for each full DL bundling window.

The Change Criterion:

In general the virtual dual-layer ACK/NACK method enables a verysignificant gain potential (e.g. 11% for above case in simulation), andso the change criterion can be made quite aggressive and only facilitatethe normal dual-layer ACK/NACK method when the UE is relatively certainthat there is a high correlation between the performance of each of thelayers throughout the entire bundling period. The change criterion canof course also be configurable by network signaling (e.g., systeminformation, dedicated UE signaling upon handover, etc.) but the moretypical case is that the eNB and UE follow some predetermined changecriterion that is somewhat persistent if not permanent.

As simple example consider the following reformulation of the abovealgorithm to clarify the change criteria.

 IF UE has been scheduled on exactly the same physical resources   (PRBs) during all active DL assignments inside bundling window    USEnormal dual-layer ACK/NACK method. OTHERWISE    USE virtual dual-layerACK/NACK method END

Of course other implementations of this concept may choose otherbalances, e.g. “exact” can be re-formulated as “overlapping” requiringthat just a single PRB is used in all the DL assignments. This is seenas a bit less aggressive (the extent of how less aggressive depends onthe extent of the overlap that triggers the switch between normal andvirtual modes, PRBs that are identical across x number of active DLassignments), and as above the inventors' initial simulations show again to be exploited by more aggressive use of the virtual mode.

It should be noted that the above definition of “exactly the samephysical resources” could be extended to be any combination of:

-   -   PRBs allocated    -   MCS selected (for both layers)    -   PMI (precoding matrix index) information

Any various combinations of these can be used to determine the propercorrelation between layers so as to employ a change criterion for whichmaximum gain would be achieved.

Reference is now made to FIG. 3 for illustrating a simplified blockdiagram of various electronic devices that are suitable for use inpracticing the exemplary embodiments of this invention. In FIG. 3 awireless network 9 is adapted for communication between a UE 10 and aNode B 12 (eNB). The network 9 may include a gateway GW/mobilitymanagement entity MME/radio network controller RNC 14 or other radiocontroller function known by various terms in different wirelesscommunication systems. The UE 10 includes a digital processor (DP) 10A,a memory (MEM) 108 that stores a program (PROG) 10C, and a suitableradio frequency (RF) transceiver 10D coupled to one or more antennas 10E(two shown) for bidirectional wireless communications over one or morewireless links 20 with the eNB 12.

The terms “connected,” “coupled,” or any variant thereof, mean anyconnection or coupling, either direct or indirect, between two or moreelements, and may encompass the presence of one or more intermediateelements between two elements that are “connected” or “coupled”together. The coupling or connection between the elements can bephysical, logical, or a combination thereof. As employed herein twoelements may be considered to be “connected” or “coupled” together bythe use of one or more wires, cables and printed electrical connections,as well as by the use of electromagnetic energy, such as electromagneticenergy having wavelengths in the radio frequency region, the microwaveregion and the optical (both visible and invisible) region, asnon-limiting examples.

The eNB 12 also includes a DP 12A, a MEM 12B, that stores a PROG 12C,and a suitable RF transceiver 12D coupled to one or more antennas 12E(two shown). The eNB 12 may be coupled via a data path 30 (e.g., lub orS1 interface) to the serving or other GW/MME/RNC 14. The GW/MME/RNC 14includes a DP 14A, a MEM 14B that stores a PROG 14C, and a suitablemodem and/or transceiver (not shown) for communication with the eNB 12over the lub link 30.

Also within the eNB 12 is a scheduler 12F that schedules the various UEsunder its control for the various UL and DL subframes. Once scheduled,the eNB sends messages to the UEs with the scheduling grants (typicallymultiplexing grants for multiple UEs in one message, such as the PDCHnoted above). Generally, the eNB 12 of an LTE system is fairlyautonomous in its scheduling and need not coordinate with the GW/MME 14excepting during handover of one of its UEs to another eNB or an accessnode of another radio access system.

At least one of the PROGs 10C, 12C and 14C is assumed to include programinstructions that, when executed by the associated DP, enable theelectronic device to operate in accordance with the exemplaryembodiments of this invention, as detailed above. Inherent in the DPs10A, 12A, and 14A is a clock to enable synchronism among the variousapparatus for transmissions and receptions within the appropriate timeintervals and slots required, as the scheduling grants and the grantedresources/subframes are time dependent.

The PROGs 10C, 12C, 14C may be embodied in software, firmware and/orhardware, as is appropriate. In general, the exemplary embodiments ofthis invention may be implemented by computer software stored in the MEM10B and executable by the DP 10A of the UE 10 and similar for the otherMEM 12B and DP 12A of the eNB 12, or by hardware, or by a combination ofsoftware and/or firmware and hardware in any or all of the devicesshown.

In general, the various embodiments of the UE 10 can include, but arenot limited to, mobile stations, cellular telephones, personal digitalassistants (PDAs) having wireless communication capabilities, portablecomputers having wireless communication capabilities, image capturedevices such as digital cameras having wireless communicationcapabilities, gaming devices having wireless communication capabilities,music storage and playback appliances having wireless communicationcapabilities, Internet appliances permitting wireless Internet accessand browsing, as well as portable units or terminals that incorporatecombinations of such functions.

The MEMs 10B, 12B and 14B may be of any type suitable to the localtechnical environment and may be implemented using any suitable datastorage technology, such as semiconductor-based memory devices, magneticmemory devices and systems, optical memory devices and systems, fixedmemory and removable memory. The DPs 10A, 12A and 14A may be of any typesuitable to the local technical environment, and may include one or moreof general purpose computers, special purpose computers,microprocessors, digital signal processors (DSPs) and processors basedon a multi-core processor architecture, as non-limiting examples.

According to exemplary embodiments of the invention from the perspectiveof the UE then and with reference to FIG. 4 there is provided a memoryembodying a computer program that is executable by a processor forperforming actions directed to sending a reply to allocated downlinkresources, and an apparatus and a method that includes at block 402receiving an allocation of downlink resources and monitoring theallocated downlink resources for data (on l layers for data, in which lis an integer), generating a resource-specific bit for each of therespectively monitored allocated downlink resources, at block 404selecting from among at least two distinct aggregations based on apattern of the allocated downlink resources where each aggregationaggregates at least a portion of the allocated downlink resources (e.g.,selecting between a first algorithm that bundles the downlink resourcesin a first mode and a second algorithm that bundles the downlinkresources in a second mode), at block 406 generating a reply bit usingthe selected aggregation (e.g., using the selected first or secondalgorithm on the generated resource-specific bits that correspond to thedownlink resources as bundled according to the respective first orsecond mode to generate l reply bits), and at block 408 transmitting thegenerated reply bits (l reply bits).

In accordance with a more particularized embodiment, one of theaggregations is across a single layer for all of the downlink resourcesand another of the aggregations is for only a portion of the downlinkresources across at least two layers. Further and more particularized isthat the reply bit is a first reply bit and the single layer is a firstlayer, and wherein each distinct aggregation generates two bits suchthat the said one of the aggregations generates a reply bit for all ofthe allocated resource across each of at least two layers, and the saidanother of the aggregations generates a reply bit across all of the atleast two layers for different subgroups of the downlink resources.

In accordance with another more particularized embodiment, selectingfrom among at least two aggregations includes selecting between twoaggregations, and the selecting is based on a change criterionindicative of how correlated in time are the allocated downlinkresources. Further and more particularized is where the change criterionis whether or not the allocated downlink resources comprise at leastoverlapping or even exactly the same physical resource blocks within abundling window that is defined by either of the two differentaggregations.

In accordance with another more particularized embodiment, the reply bitis an acknowledgement or negative acknowledgement of data received ornot received on the allocated resources, and wherein selecting fromamong at least two aggregations includes selecting between a firstaggregation that is a logical AND operation of all acknowledgement ornegative acknowledgment bits for all of the allocated resources perlayer and a second aggregation that is a logical AND operation of allacknowledgement or negative acknowledgment bits for a subgroup of theallocated resources across multiple layers. Further and moreparticularized is where the selected aggregation generates twoacknowledgement or negative acknowledgement bits for different bundlingwindows of the allocated downlink resources, one of which is allallocated downlink resources per layer and another of which is differentsubgroups of the allocated downlink resources across all layers.

From the perspective of the network, the actions are the mirror image ofthe signalling detailed above: the network sends the allocation andsends data on the allocated downlink resources, and receives the replybit from the UE. Different from the UE, if the reply bit is anacknowledgement the network does not retransmit any of the data itpreviously sent on any of the allocated downlink resources. If insteadthe reply is a negative acknowledgement, the network selects from amongat least two distinct aggregations based on the allocation of downlinkresources where each aggregation aggregates at least a portion of theallocated downlink resources, determines a bundling window and layercombination from the selected aggregation, and retransmits the data thatit sent previously in the allocated downlink resources that areindicated by the bundling and layer combination.

Further in this regard from the network perspective, the network mayalso send to the UE signalling indicating a changeover point at whichone or another of the aggregations are to apply, such as the changecriterion detailed above. This may be sent by the MME or other highernetwork node to the eNB and then signaled to the UE, and is preferablydone in signaling in a higher layer than the physical layer (e.g.,medium access control layer).

For the aspects of this invention related to the network, embodiments ofthis invention may be implemented by computer software executable by adata processor of the eNB 12, such as the processor 12A shown, or byhardware, or by a combination of software and hardware. For the aspectsof this invention related to the portable devices accessing the network,embodiments of this invention may be implemented by computer softwareexecutable by a data processor of the UE 10, such as the processor 10Ashown, or by hardware, or by a combination of software and hardware.Further in this regard it should be noted that the various logical stepdescriptions above may represent program steps, or interconnected logiccircuits, blocks and functions, or a combination of program steps andlogic circuits, blocks and functions.

In general, the various embodiments may be implemented in hardware orspecial purpose circuits, software (computer readable instructionsembodied on a computer readable medium), logic or any combinationthereof. For example, some aspects may be implemented in hardware, whileother aspects may be implemented in firmware or software which may beexecuted by a controller, microprocessor or other computing device,although the invention is not limited thereto. While various aspects ofthe invention may be illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it is wellunderstood that these blocks, apparatus, systems, techniques or methodsdescribed herein may be implemented in, as non-limiting examples,hardware, software, firmware, special purpose circuits or logic, generalpurpose hardware or controller or other computing devices, or somecombination thereof

Embodiments of the inventions may be practiced in various componentssuch as integrated circuit modules. The design of integrated circuits isby and large a highly automated process. Complex and powerful softwaretools are available for converting a logic level design into asemiconductor circuit design ready to be etched and formed on asemiconductor substrate.

Programs, such as those provided by Synopsys, Inc. of Mountain View,Calif. and Cadence Design, of San Jose, Calif. automatically routeconductors and locate components on a semiconductor chip using wellestablished rules of design as well as libraries of pre-stored designmodules. Once the design for a semiconductor circuit has been completed,the resultant design, in a standardized electronic format (e.g., Opus,GDSII, or the like) may be transmitted to a semiconductor fabricationfacility or “fab” for fabrication.

Various modifications and adaptations may become apparent to thoseskilled in the relevant arts in view of the foregoing description, whenread in conjunction with the accompanying drawings. However, any and allmodifications of the teachings of this invention will still fall withinthe scope of the non-limiting embodiments of this invention.

Although described in the context of particular embodiments, it will beapparent to those skilled in the art that a number of modifications andvarious changes to these teachings may occur. Thus, while the inventionhas been particularly shown and described with respect to one or moreembodiments thereof, it will be understood by those skilled in the artthat certain modifications or changes may be made therein withoutdeparting from the scope of the invention as set forth above, or fromthe scope of the ensuing claims.

What is claimed is:
 1. A method comprising: receiving an allocation ofdownlink resources and monitoring the allocated downlink resources on llayers for data, in which l is an integer; generating aresource-specific bit for each of the respectively monitored allocateddownlink resources; based on a pattern of the allocated downlinkresources, selecting from among at least a first algorithm that bundlesthe downlink resources in a first mode and a second algorithm thatbundles the downlink resources in a second mode; using the selectedfirst or second algorithm on the generated resource-specific bits thatcorrespond to the downlink resources as bundled according to therespective first or second mode to generate l reply bits; andtransmitting the generated l reply bits.